1. Field of the Invention
This invention relates to a process for producing a flowable fungicide formulation.
2. Description of the Prior Art
In the art of fungicide formulation, three types of commercial products are commonly available today. These types of products are as follows:
1. True liquid solutions--made by dissolving an active fungicidal compound in a suitable solvent (e.g., xylene); PA1 2. Wettable powders--made by grinding an active fungicidal compound with a selected inert clay (e.g., silica-containing material) in air mill, roller mill, ball mill or the like to obtain a fine powder having a particle size of about 1 to about 5 microns; PA1 3. Flowable formulations--made by grinding an active fungicidal compound with a clay to obtain a small particle size either before or after forming a suspension of solids in water by a thorough mixing step (e.g., in a high shear mixer). PA1 (a) heating sufficiently a mixture of at least one solid active fungicidal compound, hydrocarbon solvent and surfactant so as to form a melt; PA1 (b) adding sufficient aqueous solution to said melt to form a water-in-oil emulsion; PA1 (c) thoroughly mixing said emulsion in the presence of sufficient thickening agent to form a stable flowable fungicide formulation.
Because of handling problems and lack of ease in application with solid materials like wettable powders, farmers have favored liquid application of fungicides to soil, seeds and agricultural vegetation. Moreover, because true liquid solutions generally can be made more cheaper than flowables, fungicide manufactures have generally favored the making of the former type of formulation.
However, for certain kinds of applications, true liquid solutions of fungicidal material are not preferred. For example, the employment of flowable formulations has been favored over true solutions for the fungicidal treatment of agricultural seeds. A principal reason for this favorism is that seeds which have been treated with a fungicide are normally required by governmental regulations to be dyed an unnatural color (e.g., bright red or violet) to disassociate treated seeds from untreated seeds. Accordingly, fungicide formulations employed in seed treatment also contain a minor amount of a dye. It has been found that flowables are better able to transfer that dye to the seeds than conventional true solutions.
Another obstacle which prevents the universal use of true solutions of fungicides has to do with the selection of a suitable solvent. Such solvents must possess several properties. They must be inert to the active fungicidal material so as to not inactive its fungicidal properties. Furthermore, the solvent must still be able to dissolve it; and yet be harmless to the crops and agricultural environment being treated. Xylene, because it generally possesses such suitable properties, has been the solvent of choice for many fungicial applications. But, there are problems associated with xylene. This solvent possesses an odor which is objectionable, causing complaints from handlers and farmers. Also, the solvent has a flash point of about 80.degree. F., causing the products to carry a flammable label for transportation, which means higher freight rates and more restrictions on transportation, storage and use. Furthermore, distributors and farmers who employ xylene may have their insurance rates raised because of its "flammable" property. Further, because xylene is an aromatic petroleum product, its supply is increasingly smaller. Still further, when xylene-dissolved products are used in seed treatments, the presence of xylene appears to dull the brightness of the dyed color on the seeds, thus making it more difficult to disassociate treated seeds from untreated seeds.
With such problems surrounding true liquid solutions of fungicides, farmers are increasingly turning to the use of flowable formulations, especially in the treatment of seeds. However, in the past, the production of flowable formulations has been relatively time consuming and expensive, mainly because of the grinding step that is necessary to reduce the size of solid fungicidal compounds. This size reduction is necessary to allow the fungicide materials to remain in the suspension. But, such grinding steps require relatively expensive equipment and are carried out at a slow rate. Thus, until now, it has been normally uneconomical to make flowable fungicide formulations starting with solid, as opposed to liquid, active fungicidal compounds.
Therefore, there is a need in the art to find a new process for producing flowable fungicide that can economically utilize solid fungicidal compounds without grinding. The present invention is directed to a process that eliminates such unwanted grinding steps.